Preoperative diagnosis
The clinical manifestation of UCSS is lack of specificity, which makes it difficult to diagnose before and during the operation. In our series, 91 patients (57.2%) were diagnosed by TTE before operation, and 6 patients (3.77%) were diagnosed by CT. Before 2008, only 14 of the 46 cases were preoperative diagnosed as UCSS (30.4%), and after 2008, 81 of 113 (71.7%) cases were diagnosed before operation. It was precisely because of the increased understanding of the pathological anatomy and pathophysiological features of UCSS, the rate of preoperative diagnosis of UCSS in our hospital has improved significantly in recent years. It was reported that the accuracy of UCSS diagnosis by preoperative TTE and acoustic angiography was 65% [4], and the diagnosis rate of this series was quite similar after 2008.
TTE examination was easy to detect CS expansion, and suprasternal fossae scanning was easy to make it clear the presence of LSVC and the communication via LIV and RSVC, while 80%~90% LSVC patients without communications [5]. If the ultrasound didn’t detect the CS, it suggested completely unroofed type I or type Ⅱ. Therefore, careful attention should be paid to TTE or intraoperative exploration to avoid missed diagnosis. Cardiac catheterization examination via the left upper limb venous catheterization was easy to find LSVC; if catheterization via the right upper limb vein and catheter tip through the right atrium and then appeared in the left superior mediastinum, it also suggested the presence of LSVC. It was reported that it was more likely to diagnose UCSS using transesophageal echocardiography (TEE), real-time three-dimensional echocardiography, or magnetic resonance imaging (MRI)[6-8]. In recent years, several cases of TTE diagnosis errors have been reported, which have been diagnosed as UCSS by TEE, MDCT or MRI [9-11].
Although preoperative diagnostic rates have improved markedly in recent years, careful intraoperative intracardiac and extracardiac inspection remains critical. In our series, 62 cases (37.1%) were diagnosed by intraoperative inspection. If it is found in intraoperative extracardiac inspection that LSVC does not converge to the CS but directly into the LA, the malformation should be considered. If the expansion of CS is detected in the right atrium, or red blood flows out of it, or the CS opening can’t be found, we should think more of the presence of this malformation. When necessary, open the atrial septum and inspect the left and right atrium together to diagnose [12].